The MO Historical Review, some years ago, had good maps included in an article on the slave population of the counties.
It was very obvious where the S. Aristocratic and politically active settlers put down roots along the major river avenues. These provided transportation for MO, and were bordered by land suitable for the intensive labor they felt required laborers, being from the South, this meant slaves. This group of families ran the politics of MO, hence Gov. Claiborne Fox Jackson, Former Gov. Sterling Price, the Marmadukes, Dr. Sappingtons' family, and other such men. Their political circles were rather exclusive. They were educated into and accustomed to politics and power. They knew how the system worked.
ALA